/Engine/Plugins/Experimental/Mutable/Source/MutableRuntime/Public/MuR/Instance.h
Find the base surface index and Lod index when reusing surfaces between LODs. Return the surface index and the LOD it belongs to.
void FindBaseSurfaceBySharedId ( int32 CompIndex, int32 SharedId, int32 & OutSurfaceIndex, int32 & OutLODIndex ) const